Abstract: The deformation and energy-absorbing characteristics of broadside defense cabins with different structures are compared to study the feasibility of the application of sandwich structure in the broadside defense cabin. Four structural forms of broadside defense cabin cabins were designed，and 300 g TNT underwater contact explosion damage tests were carried out，respectively. Through comparative analysis of the deformation and destruction of the inner bulkheads of four broadside defense cabins，it is concluded that the boundary must have a strong support structure for a structure that uses the large flexible deformation of inner wall of the tank to absorb energy，and it is difficult to exert the tensile energy absorption effect of film when the support is insufficient.For the sandwich structure of the energy-absorbing tank that utilizes the integral deformation and energy absorption of inner wall of tank，the arc-shaped plate and inner wall of energy-absorbing tank，the arc-shaped plate provides strong support for the inner wall of tank and can deform and absorb energy together with the inner wall of tank，thus ffectively improving the protection ability of broadside defense cabin. a foam aluminum layer is added between the arc-shaped plates，failing to achieve a better protection effect.The arc-shaped plate is moved forward to the sandwich structure of the liquid tank， and the setting of arc-shaped plate causes the energy in the water to be not fully dissipated to the entire tank，and the accumulation of energy causes more serious damage to the internal tank.

Key words: broadsidedefensecabin, energyabsorbingstructure, underwatercontactexplosion, sandwichstructure, protectiveperformance